The present invention relates generally to a process and system for making a hologram-recording dry plate. In particular, this invention is directed to a process and system for fabricating a transmission hologram-recording dry plate provided with a layer for preventing halation during recording or reproduction as well as a reflection hologram-recording dry plate provided with a colored layer or an antireflection layer for preventing formation of unnecessary interference fringes by interface reflection at an air/dry plate interface during recording or reproduction.
For the recording or reproduction of a transmission hologram, object light and reference light are entered in a hologram-recording dry plate from its surface side. However, the object light and reference light arriving at the back side of the dry plate is reflected thereat, resulting in halation. As halation occurs, unnecessary interference fringes are recorded in the dry plate and so the reconstruction capability of the hologram becomes worse. For this reason, the transmission hologram-recording dry plate has so far been provided on its back surface with a layer (anti-halation layer) for absorbing transmitted laser light, thereby reducing the occurrence of undesired interference fringes ascribed to the reflection of laser light at the back surface. The anti-halation layer is generally provided on the back surface of the dry plate by the coating and drying of a resin solution with a dye dissolved therein. For instance, an intimate mixture of a suitable amount of dye with a methyl ethyl ketone solution of polyvinyl butyral (PVB) may be used.
However, one problem with this method is that its productivity is low because of comprising a complicated process including the coating and drying of the resin solution, and another problem is contamination of the front surface of the photosensitive material with a portion of the coated solution that comes from the back surface. In applications where high cleanliness is required, additional steps of wiping away the anti-halation layer with a solvent after recording are used, thereby achieving complete removal thereof. As an example, JP-A 9-54539 proposes a transmission hologram-recording dry plate wherein an anti-halation layer is used in a dry film form that enables a conventional fabrication process to be greatly simplified and can fit well for a laminator. This publication also comes up with a fabrication process and system.
For the recording or reproduction of a reflection hologram, reference light is entered in a hologram-recording dry plate from its front surface while object light (diffracted light from a subject or hologram plate) is entered in the hologram-recording dry plate from its back surface. Upon reaching an air/dry plate interface, however, the object or reference light is reflected thereat, resulting in halation. As halation occurs, unnecessary interference fringes are recorded in the dry plate and so the reconstruction capability of the hologram becomes worse. Usually, therefore, an antireflection glass or colored glass (ND (neutral density) glass) for preventing reflection at the interface is provided on the air/dry plate interface of the reflection hologram dry plate.
The antireflection glass is laminated on the interface with an optical contact liquid located between them. However, the optical contact liquid is poor in workability, because it is difficult to have a uniform thickness due to flowing, vibration, air entrapment, etc., and especially because when used in a large amount, long time is needed until it is kept stationary and stabilized after coating. To solve these problems, for instance, JP-A 5-281883 and Japanese Patent Application Nos. 7-281583 and 7-114329 propose a process of fabricating a hologram dry plate without recourse to any contact liquid, wherein a flexible colored or antireflection film is used instead of the glass.
With a conventional transmission hologram-recording dry plate fabrication process and system such as one disclosed in the aforesaid JP-A 9-54539, it is possible to fabricate both a transmission hologram-recording dry plate and a reflection hologram-recording dry plate. When a roll form of film having a separator is intermittently fed, however, it is impossible to prevent film defects caused by the pressure of a guide roller or the like, and the occurrence and deposition of dust caused by sheet-cutting. In applications where high precision and cleanliness are needed, it is thus impossible to achieve a transmission or reflection hologram-recording dry plate that has always sufficient properties.